The NodeJS implementation of Knyle Style Sheets (KSS) developed by Hugh Kennedy is super handy. With one simple command after you have set it up you can generate a living style guide. Having to always update your style guide is generally a chore. This saves the day.
Boilerplates, bootstraps or whatever you want to call them have become a valuable resource for any web developer. Not only do they provide great knowledge into the best practices to use, they also save us vast amounts of time.
Back in the day, there was great pleasure in coding something up from scratch. In this day and age, I think most people are more than happy to start with a base, whatever that base might be. All of the resources listed below can be used in any way that suits you.